1. Field of the Invention
This invention relates to bicycle frames, and more particularly to bicycle frames of the tubular type for light-weight, high performance bicycles.
2. Prior Art
Evolution of the technological development of bicycles has been summarized in Scientific American, pages 81-91, Mar. 1973 by S. Wilson. As noted therein, notwithstanding the fact that the classic diamond shaped frame takes much of the riding strains directly, such a frame is still subject to bending and torsional stresses, particularly when the rider exerts pressure first on one pedal and then the second pedal. Also noted in the article is the fact that tubular construction has been employed for bicycle frames, particularly for racing bicycles, in order to reduce the weight of the bicycle. This concern with frame rigidity and bike weight are two interrelated factors which are most significant, particularly for high performance racing bicycles. The lower the bike weight, the greater the pedalling responsiveness of the bicycle. Similarly, the more rigid the frame, the greater the pedalling ease. For racing bikes, lightweight, high strength materials such as titanium and other alloys have been proposed for the tubular elements of the bicycle frame. Practical experience has shown, however, that, notwithstanding the fact that individual tubular elements through modern metallurgical techniques can be made exceedingly stiff, the bicycle frame having classical diamond shape constructed from such tubular materials nonetheless is very whippy when tested under racing conditions. Indeed, considerable instability is manifested by bicycles which are constructed from such types of tubular members.